Stroke treatment consists of two categories: prevention and acute management. Prevention treatments currently consist of antiplatelet agents, anticoagulation agents, surgical therapy, angioplasty, lifestyle adjustments, and medical adjustments. An antiplatelet agent commonly used is aspirin. The use of anticoagulation agents seems to have no statistical significance. Surgical therapy appears to be effective for specific sub-groups. Angioplasty is still an experimental procedure with insufficient data for analysis. Lifestyle adjustments include quitting smoking, regular exercise, regulation of eating, limiting sodium intake, and moderating alcohol consumption. Medical adjustments include medications to lower blood pressure, lowering cholesterol, controlling diabetes, and controlling circulation problems.
Acute management treatments consist of the use of thrombolytics, neuroprotective agents, Oxygenated Fluorocarbon Nutrient Emulsion (OFNE) Therapy, Neuroperfusion, GPIIb/IIIa Platelet Inhibitor Therapy, and Rehabilitation/Physical Therapy.
A thrombolytic agent induces or moderates thrombolysis, and the most commonly used agent is tissue plasminogen activator (t-PA). Recombinant t-PA (rt-PA) helps reestablish cerebral circulation by dissolving (lysing) the clots that obstruct blood flow. It is an effective treatment, with an extremely short therapeutic window; it must be administered within 3 hours from onset. It also requires a CT scan prior to administration of the treatment, further reducing the amount of time available. Genetech Pharmaceuticals manufactures ACTIVASE® and is currently the only source of rt-PA.
Neuroprotective agents are drugs that minimize the effects of the ischemic cascade, and include, for example, Glutamate Antagonists, Calcium Antagonists, Opiate Antagonists, GABA-A Agonists, Calpain Inhibitors, Kinase Inhibitors, and Antioxidants. Several different clinical trials for acute ischemic stroke are in progress. Due to their complementary functions of clot-busting and brain-protection, future acute treatment procedures will most likely involve the combination of thrombolytic and neuroprotective therapies. However, like thrombolytics, most neuroprotectives need to be administered within 6 hours after a stroke to be effective.
Oxygenated Fluorocarbon Nutrient Emulsion (OFNE) Therapy delivers oxygen and nutrients to the brain through the cerebral spinal fluid. Neuroperfusion is an experimental procedure in which oxygen-rich blood is rerouted through the brain as a way to minimize the damage of an ischemic stroke. GPIIb/IIIa Platelet Inhibitor Therapy inhibits the ability of the glycoprotein GPIIb/IIIa receptors on platelets to aggregate, or clump. Rehabilitation/Physical Therapy must begin early after stroke, however, they cannot change the brain damage. The goal of rehabilitation is to improve function so that the stroke survivor can become as independent as possible. L0091 Although some of the acute treatments showed promise in clinical trials, a study conducted in Cleveland showed that only 1.8% of patients presenting with stroke symptoms even received the t-PA treatment (Katzan, et al., Use of tissue-type plasminogen activator for acute ischemic stroke: the Cleveland area experience. JAMA. 2000 Mar. 1; 283(9):1151-1158). t-PA is currently the most widely used of the above-mentioned acute stroke treatments, however, the number of patients receiving any new “effective” acute stroke treatment is estimated to be under 10%. These statistics show a clear need for the availability of acute stroke treatment at greater than 24 hours post stroke.
For some of these acute treatments (i.e., t-PA) the time of administration is crucial. Recent studies have found that the average time of arrival at the hospital is between 3 and 6 hours after stroke (Evenson, et al., Prehospital and in-hospital delays in acute stroke care. Neuroepidemiology. 2001 May; 20(2):65-76) t-PA has been shown to enhance recovery of ˜⅓ of the patients that receive the therapy, however a recent study mandated by the FDA (Albers, et al., Intravenous tissue-type plasminogen activator for treatment of stroke: the standard treatment with alteplase to reverse stroke (STARS) study. JAMA. 2000 Mar. 1; 283(9):1 145-50) found that about a third of the time the three-hour treatment window was violated resulting in an ineffective treatment. With the exception of rehabilitation, the remaining acute treatments are still in clinical trials and are not widely available in the U.S., particularly in rural areas, which may not have large medical centers with the needed neurology specialists and emergency room staffing, access to any of these new methods of stroke diagnosis and therapy may be limited for some time.
Human umbilical cord blood (hUCB) may be preferable to other cell sources such as bone marrow due to hUCB cells' low pathogenicity and immune immaturity. The mononuclear cell fraction from human hUCB (MNC hUCB) is relatively rich in multipotent progenitors and has extensive proliferation capacity (Mayani, & Lansdorp, Biology of human umbilical cord blood-derived hematopoietic stem/progenitor cells. Stem Cells. 1998; 16(3):153-165; Todaro, et al., Haematopoietic progenitors from umbilical cord blood. Blood Purif. 2000; 18(2):144-147). A number of studies have shown that intravenously administering MNC hUCB (Saneron's proprietary fraction U-CORD-CELL™). MNC hUCB were hypothesized to provide neuroprotective and/or trophic effects for motor neurons by modulating the host immune inflammatory system through release of various growth or anti-inflammatory factors. Additionally, hUCB plasma (hUCBP) is a rich source of cytokines and other proteins such as insulin-like growth factor-1 (IGF-1), transforming growth factor (TGF)-β and vascular endothelial growth factor (VEGF) required for growth and survival of hematopoietic stem cells (Broxmeyer, et al., Commentary: a rapid proliferation assay for unknown co-stimulating factors in cord blood plasma possibly involved in enhancement of in vitro expansion and replating capacity of human hematopoietic stem/progenitor cells. Blood Cells. 1994; 20 (2-3):492-497; Kim, et al., Ex vivo expansion of human umbilical cord blood-derived T-lymphocytes with homologous cord blood plasma. Tohoku J. Exp. Med. 2005 February; 205(2):115-122; Lam, et al., Preclinical ex vivo expansion of cord blood hematopoietic stem and progenitor cells: duration of culture; the media, serum supplements, and growth factors used; and engraftment in NOD/SCID mice. Transfusion. 2001 December; 41(12):1567-1576). Moreover, it has been shown that hUCB serum contains more neurotrophic factors (substance P, IGF-1, nerve growth factor [NGF]) compared to the peripheral blood serum effectively used for the treatment of the persistent corneal epithelial defects (Vajpayee, et al., Evaluation of umbilical cord serum therapy for persistent conical epithelial defects. Br. J. Ophthalmol. 2003 November; 87(11):1312-1316), neurotrophic keratitis (Yoon, et al., Application of umbilical cord serum eyedrops for the treatment of neurotrophic keratitis. Ophthalmology. 2007 September; 114(9):1637-1642), and recurrent conical erosion (Yoon, et al., Application of umbilical cord serum eyedrops for recurrent conical erosions. Cornea. 2011 July; 30(7):744-748).
Borlongan, et al. (U.S. Pat. No. 7,674,457) provides blood brain barrier permeabilizers, like mannitol, can facilitate entry of stem cells form the periphery into the CNS during acute stages of stroke. However, it was unclear whether BBB permeabilization during chronic stages of stroke also facilitate entry of stem cells from the periphery to the injured brain.
Transplantation of stem cells has been proposed as a means of treating stroke. Neural stem cells are important treatment candidates for stroke and other CNS diseases because of their ability to differentiate in vitro and in vivo into neurons, astrocytes and oligodendrocytes. The powerful multipotent potential of stem cells may make it possible to effectively treat diseases or injuries with complicated disruptions in neural circuitry, such as stroke where more than one cell population is affected.
Despite this great potential, an easily obtainable, abundant, safe, and clinically proven source of stem cells has been elusive until recently. Umbilical cord blood contains a relatively high percentage of hematopoietic stem cells capable of differentiating into all of the major cellular phenotypes of the CNS, including neurons, oligodendrocytes, and glial cells (Sanchez-Ramos, et al., Expression of neural markers in human umbilical cord blood. Exp Neurol. 2001 September; 171(1):109-115; Bicknese, et al., Human umbilical cord blood cells can be induced to express markers for neurons and glia. Cell Transplant. 2002; 11(3):261-264). Following intravenous delivery, human umbilical cord blood (HUCB) cells survive and migrate into the CNS of normal and diseased animals and have been shown to promote functional recovery in animal models of stroke, spinal cord injury, and hemorrhage (Chen, et al., Intravenous administration of human umbilical cord blood reduces behavioral deficits after stroke in rats. Stroke, 2001 November; 32(11):2682-2688; Lu, et al., Intravenous administration of human umbilical cord blood reduces neurological deficit in the rat after traumatic brain injury. Cell Transplant. 2002; 11(3):275-281; Saporta, et al., Human umbilical cord blood stem cells infusion in spinal cord injury: engraftment and beneficial influence on behavior. J. Hematother Stem Cell Res. 2003 June; 12(3):271-278).
In addition to the growing body of evidence supporting the neurotherapeutic potential of hUCBC, there is a long and well-established series of practical advantages of using hUCBC for clinical diseases. Cord blood is easily obtained with no risks to the mother or child. A blood sample is taken from the umbilical vein attached to the placenta after birth. The percentage of the primitive stem cells present in the mononuclear fraction is small, but the absolute yield of stem cells available may number in the thousands prior to expansion or other ex vivo manipulation, providing an easily obtainable and plentiful source. Hematopoietic stem cells from hUCB have been routinely and safely used to reconstitute bone marrow and blood cell lineages in children with malignant and nonmalignant diseases after treatment with myeloablative doses of chemoradiotherapy (Lu, et al., Stem cells from bone marrow, umbilical cord blood and peripheral blood for clinical application: current status and future application. Crit Rev Oncol Hematol. 1996 March; 22(2):61-78; Broxmeyer, ed., Cellular characteristics of cord blood and cord blood transplantation. in press. (AABB Press, 1998, Bethesda, Md.). Early results indicate that a single cord blood sample provides enough hematopoietic stem cells to provide both short- and long-term engraftment. This suggests that these stem cells maintain extensive replicative capacity, which may not be true of hematopoietic stem cells obtained from the adult bone marrow.